[PATCH v2 1/2] perf expr: Add d_ratio operation

Ian Rogers
2020-06-10T23:58:35Z

d_ratio avoids division by 0 yielding infinity, such as when a counter
doesn't get scheduled. An example usage is:

{
"BriefDescription": "DCache L1 misses",
"MetricExpr": "d_ratio(MEM_LOAD_RETIRED.L1_MISS, MEM_LOAD_RETIRED.L1_HIT + MEM_LOAD_RETIRED.L1_MISS + MEM_LOAD_RETIRED.FB_HIT)",
"MetricGroup": "DCache;DCache_L1",
"MetricName": "DCache_L1_Miss",
"ScaleUnit": "100%",
}

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/tests/expr.c | 2 ++
tools/perf/util/expr.l | 1 +
tools/perf/util/expr.y | 14 ++++++++++++--
3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
index 1cb02ca2b15f..c4877b36ab58 100644
--- a/tools/perf/tests/expr.c
+++ b/tools/perf/tests/expr.c
@@ -39,6 +39,8 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
ret |= test(&ctx, "1+1 if 3*4 else 0", 2);
ret |= test(&ctx, "1.1 + 2.1", 3.2);
ret |= test(&ctx, ".1 + 2.", 2.1);
+ ret |= test(&ctx, "d_ratio(1, 2)", 0.5);
+ ret |= test(&ctx, "d_ratio(2.5, 0)", 0);

if (ret)
return ret;
diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
index f397bf8b1a48..298d86660a96 100644
--- a/tools/perf/util/expr.l
+++ b/tools/perf/util/expr.l
@@ -100,6 +100,7 @@ symbol ({spec}|{sym})+
}
}

+d_ratio { return D_RATIO; }
max { return MAX; }
min { return MIN; }
if { return IF; }
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index bf3e898e3055..fe145344bb39 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -10,6 +10,14 @@
#include "smt.h"
#include <string.h>

+static double d_ratio(double val0, double val1)
+{
+ if (val1 == 0) {
+ return 0;
+ }
+ return val0 / val1;
+}
+
%}

%define api.pure full
@@ -28,7 +36,7 @@
%token <num> NUMBER
%token <str> ID
%destructor { free ($$); } <str>
-%token MIN MAX IF ELSE SMT_ON
+%token MIN MAX IF ELSE SMT_ON D_RATIO
%left MIN MAX IF
%left '|'
%left '^'
@@ -64,7 +72,8 @@ other: ID
}
|
MIN | MAX | IF | ELSE | SMT_ON | NUMBER | '|' | '^' | '&' | '-' | '+' | '*' | '/' | '%' | '(' | ')' | ','
-
+|
+D_RATIO

all_expr: if_expr { *final_val = $1; }
;
@@ -105,6 +114,7 @@ expr: NUMBER
| MIN '(' expr ',' expr ')' { $$ = $3 < $5 ? $3 : $5; }
| MAX '(' expr ',' expr ')' { $$ = $3 > $5 ? $3 : $5; }
| SMT_ON { $$ = smt_on() > 0; }
+ | D_RATIO '(' expr ',' expr ')' { $$ = d_ratio($3,$5); }
;

%%
--
2.27.0.278.ge193c7cf3a9-goog